Around it, high-rise buildings with a mix of apartments, offices and shops form a bustling urban center. People use public transportation more and their cars less. They stroll on wide sidewalks past storefronts, greenery and public art.

The plan, which proposes zoning changes and new standards for developers, is intended to transform the area into a walkable community. At present, the area is a combination of expansive parking lots, monolithic office buildings, single-family homes and garden apartments. The main retail offerings are in shopping centers along Annapolis Road, a six-lane highway.

"The season for mega-malls and sprawl development, it's basically over," said William Washburn, the Maryland-National Capital Park and Planning Commission coordinator who is managing the New Carrollton project. "The Washington metro area, like the rest of the nation, is facing real challenges in terms of fiscal ability to maintain services. . . . Sprawl development is becoming harder and harder to service."

The plan envisions five distinct "neighborhoods" in the 640-acre site, with as many as 5,500 housing units and as much as 6.1 million square feet of office and retail space.

A renovated train station would anchor the urban Metro Core neighborhood, where mixed-use high-rises would sprout around the existing Internal Revenue Service and Computer Sciences Corp. buildings. The surrounding neighborhoods would consist of smaller mixed-use structures and existing homes.

Extensive redevelopment is also planned for neighborhoods designated in the plan as the Annapolis Road Corridor and Garden City.

In the existing North Hillside residential neighborhood, the plan shows infill development replacing some buildings in the 187-unit Carrollon Manor apartment complex. The nearby Carrollan Gardens Condominiums would remain intact.

About 330 single-family homes in the West Lanham Hills-Hanson Oaks area, secluded neighborhoods at the western edge of the site, would also be left untouched.

"We think that this is in keeping with the trend that more and more jurisdictions are doing anyway," Washburn said. "Everybody in the region is looking at Arlington County," where development has flourished around Metro stops.

The five members of the county Planning Board voted unanimously to grant preliminary approval to the plan, a sign that they are likely to adopt it when they return from recess Sept. 10.